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ZackerySpytzserhiy-storchaka
ZackerySpytz
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serhiy-storchaka
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bpo-34880: Add the LOAD_ASSERTION_ERROR opcode. (GH-15073)
Fix assert statement misbehavior if AssertionError is shadowed.
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-2626
lines changed

14 files changed

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-2626
lines changed

‎Doc/library/dis.rst

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@@ -752,6 +752,14 @@ iterations of the loop.
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from the block stack.
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.. opcode:: LOAD_ASSERTION_ERROR
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Pushes :exc:`AssertionError` onto the stack. Used by the :keyword:`assert`
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statement.
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.. versionadded:: 3.9
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.. opcode:: LOAD_BUILD_CLASS
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Pushes :func:`builtins.__build_class__` onto the stack. It is later called

‎Doc/whatsnew/3.9.rst

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@@ -226,3 +226,12 @@ Changes in the Python API
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* The :mod:`venv` activation scripts no longer special-case when
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``__VENV_PROMPT__`` is set to ``""``.
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CPython bytecode changes
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------------------------
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* The :opcode:`LOAD_ASSERTION_ERROR` opcode was added for handling the
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:keyword:`assert` statement. Previously, the assert statement would not work
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correctly if the :exc:`AssertionError` exception was being shadowed.
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(Contributed by Zackery Spytz in :issue:`34880`.)

‎Include/opcode.h

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‎Lib/importlib/_bootstrap_external.py

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Original file line numberDiff line numberDiff line change
@@ -271,6 +271,7 @@ def _write_atomic(path, data, mode=0o666):
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# Python 3.8b2 3412 (Swap the position of positional args and positional
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# only args in ast.arguments #37593)
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# Python 3.8b4 3413 (Fix "break" and "continue" in "finally" #37830)
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# Python 3.9a0 3420 (add LOAD_ASSERTION_ERROR #34880)
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#
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# MAGIC must change whenever the bytecode emitted by the compiler may no
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# longer be understood by older implementations of the eval loop (usually
@@ -279,7 +280,7 @@ def _write_atomic(path, data, mode=0o666):
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# Whenever MAGIC_NUMBER is changed, the ranges in the magic_values array
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# in PC/launcher.c must also be updated.
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MAGIC_NUMBER = (3413).to_bytes(2, 'little') + b'\r\n'
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MAGIC_NUMBER = (3420).to_bytes(2, 'little') + b'\r\n'
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_RAW_MAGIC_NUMBER = int.from_bytes(MAGIC_NUMBER, 'little') # For import.c
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_PYCACHE = '__pycache__'

‎Lib/opcode.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -109,7 +109,7 @@ def jabs_op(name, op):
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def_op('LOAD_BUILD_CLASS', 71)
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def_op('YIELD_FROM', 72)
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def_op('GET_AWAITABLE', 73)
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def_op('LOAD_ASSERTION_ERROR', 74)
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def_op('INPLACE_LSHIFT', 75)
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def_op('INPLACE_RSHIFT', 76)
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def_op('INPLACE_AND', 77)

‎Lib/test/test_dis.py

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -147,7 +147,7 @@ def bug1333982(x=[]):
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dis_bug1333982 = """\
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%3d 0 LOAD_CONST 1 (0)
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2 POP_JUMP_IF_TRUE 26
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4 LOAD_GLOBAL 0 (AssertionError)
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4 LOAD_ASSERTION_ERROR
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6 LOAD_CONST 2 (<code object <listcomp> at 0x..., file "%s", line %d>)
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8 LOAD_CONST 3 ('bug1333982.<locals>.<listcomp>')
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10 MAKE_FUNCTION 0

‎Lib/test/test_exceptions.py

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Original file line numberDiff line numberDiff line change
@@ -1285,6 +1285,22 @@ def g():
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next(i)
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next(i)
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@unittest.skipUnless(__debug__, "Won't work if __debug__ is False")
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def test_assert_shadowing(self):
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# Shadowing AssertionError would cause the assert statement to
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# misbehave.
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global AssertionError
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AssertionError = TypeError
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try:
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assert False, 'hello'
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except BaseException as e:
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del AssertionError
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self.assertIsInstance(e, AssertionError)
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self.assertEqual(str(e), 'hello')
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else:
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del AssertionError
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self.fail('Expected exception')
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class ImportErrorTests(unittest.TestCase):
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‎Misc/NEWS.d/next/Core and Builtins/2019-08-01-10-45-51.bpo-34880.u_x_CG.rst

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@@ -0,0 +1,3 @@
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The :keyword:`assert` statement now works properly if the
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:exc:`AssertionError` exception is being shadowed.
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Patch by Zackery Spytz.

‎Python/ceval.c

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@@ -2242,6 +2242,13 @@ _PyEval_EvalFrameDefault(PyFrameObject *f, int throwflag)
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}
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}
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case TARGET(LOAD_ASSERTION_ERROR): {
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PyObject *value = PyExc_AssertionError;
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Py_INCREF(value);
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PUSH(value);
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FAST_DISPATCH();
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}
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case TARGET(LOAD_BUILD_CLASS): {
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_Py_IDENTIFIER(__build_class__);
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‎Python/compile.c

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Original file line numberDiff line numberDiff line change
@@ -1129,6 +1129,8 @@ stack_effect(int opcode, int oparg, int jump)
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return (oparg & FVS_MASK) == FVS_HAVE_SPEC ? -1 : 0;
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case LOAD_METHOD:
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return 1;
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case LOAD_ASSERTION_ERROR:
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return 1;
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default:
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return PY_INVALID_STACK_EFFECT;
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}
@@ -3253,16 +3255,10 @@ compiler_from_import(struct compiler *c, stmt_ty s)
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static int
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compiler_assert(struct compiler *c, stmt_ty s)
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{
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static PyObject *assertion_error = NULL;
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basicblock *end;
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if (c->c_optimize)
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return 1;
3261-
if (assertion_error == NULL) {
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assertion_error = PyUnicode_InternFromString("AssertionError");
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if (assertion_error == NULL)
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return 0;
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}
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if (s->v.Assert.test->kind == Tuple_kind &&
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asdl_seq_LEN(s->v.Assert.test->v.Tuple.elts) > 0)
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{
@@ -3277,7 +3273,7 @@ compiler_assert(struct compiler *c, stmt_ty s)
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return 0;
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if (!compiler_jump_if(c, s->v.Assert.test, end, 1))
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return 0;
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ADDOP_O(c, LOAD_GLOBAL, assertion_error, names);
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ADDOP(c, LOAD_ASSERTION_ERROR);
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if (s->v.Assert.msg) {
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VISIT(c, expr, s->v.Assert.msg);
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ADDOP_I(c, CALL_FUNCTION, 1);

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